For Yuri, I did (on JP but I don't think it differs pretty much) level to 10 every skill except the first one (BAN BAN BAN is called on JP), max the 3 FMs and both crits passives, dunno much about Mikoto, sorry :/

Here's what I run, at level 62, all PNA slots unlocked, and all SP books gotten from Story + Plane Gate quests.

Yuri:

Seulbi:

I leave Space Compression at level 9 because the Master Aerial version moves forward, which can be disastrous as it can drag enemies out of Satellite Fall's range. (I always do a Space Compression + Satellite Fall + Rail Cannon combo. Space Compression applies a Magic Defense debuff in addition to holding enemies in place.) And since the explosion at the end does some decent damage, I find the Aerial Damage bonus to be worth more than the extra duration or the damage increase from leveling it up.

Seulbi don't need physical, her physical damage (if any) is terribly minor compared to her magical one, so she is mainly magical.
In other words, max magical critical damage/raw attack/chance(or keep this one at Lv1), ignore the physical passives completely for a good build.

Oh, didn't see Miko/Seulbi at all, guessed it was only for Yuri, lol XD
But yeah, I knew that Mikoto didn't have anything really phys related. Btw, thanks for the screens, those are gonna come in handy for my chars

Honestly Skill Builds in this game are reliant on your personal taste, almost everybody has completely different build, so you need to decide for YOURSELF what you need.

I mean, this IS a game, if you aren't having fun there's no point. Also, SP isn't as restrictive as other MMORPG since you can just down whatever you think sucks with credit/free event VIP, so just experiment around. (Hopefully JP gives out those free Character VIP whenever you complete an area, idk why they wouldn't)

I say this because a lot of people tend to skip Cross Slash and Full Salvo Launch.
I take them both because it's the only way Yuri can infinite juggle, and because no one should underestimate Full Salvo Launch's DPS when you hit the Master Skill Cube effect.

Ofc, you can skip if that's your preference, but you wouldn't know it's your preference if you don't try, right?